Existing light emitting diodes (LED) are obtained either by mixing a green phosphorescent substance and a red phosphorescent substance to a blue light emitting diode, or mixing a yellow phosphorescent substance and a blue-green phosphorescent substance to a UV-light emission light emitting diode. However, such a method is difficult to control colors and accordingly, color rendering is not favorable. As a result, Color Gamut is inferior.
In order to overcome such Color Gamut decline, and reduce production costs, a method obtaining green and red by filming quantum dots and binding the result to a blue LED has been recently tried. However, cadmium series quantum dots have safety problems, and other quantum dots have significantly lower efficiency than cadmium series. In addition, quantum dots have a disadvantage in that they have inferior stability for oxygen and water, and when aggregated, the performance significantly declines. Furthermore, unit production costs are high since maintaining constant sizes is difficult when quantum dots are produced.